Sampling efficiency of flow-through air sampler: Effect of sampling rate.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Atmospheric Chemistry

Background:

• The Flow Through Sampler (FTS) is a wind-powered device for collecting air samples.
• Sampling rate fluctuations in FTS necessitate understanding their impact on pollutant breakthrough.
• Investigating the influence of sampling parameters on FTS collection efficiency is crucial for accurate environmental monitoring.

Purpose of the Study:

• To investigate the impact of sampling rate (wind velocity) on the breakthrough profiles of PCBs, PAHs, and OCPs using the FTS-PUF sampling column.
• To determine the relationship between wind velocity, compound volatility, and sampling column efficiency (theoretical plates and breakthrough volume).
• To develop a predictive model for FTS collection performance under varying environmental conditions.

Main Methods:

• Interconnected FTS sampling columns with three pumps operating at five different sampling rates (wind velocities) at 293 K and 303 K.
• Analyzed breakthrough profiles of Polychlorinated Biphenyls (PCBs), Polycyclic Aromatic Hydrocarbons (PAHs), and Organochlorine Pesticides (OCPs).
• Employed multiple linear regression and Linear Solvation Energy Relationship (LSER) analysis to correlate parameters.

Main Results:

• Number of theoretical plates (N) and logarithm of breakthrough volume (logV_B) showed linear relationships with the inverse of wind velocity (1/u).
• Compound volatility influenced the impact of wind velocity on N; volatile PCBs were most affected.
• Wind speed had a stronger influence on the breakthrough volume of less volatile compounds, correlating significantly with compound volatility (logP_L).

Conclusions:

• A predictive model was established, correlating N and logV_B with temperature and wind velocity (log(V_B/m³)=2010/(T/K)-0.00066/(u/(m/s))+0.55N-5.41).
• FTS-PUF sampling column performance can be predicted for various compounds under different temperatures and sampling rates.
• This provides valuable data for accurate monitoring of atmospheric organic pollutant concentrations.